Codeforces 584 - A problem solution

A. Olesya and Rodion

time limit per test 1 second

memory limit per test 256 megabytes

input standard input

output standard output

Olesya loves numbers consisting of n digits, and Rodion only likes numbers that are divisible by t. Find some number that satisfies both of them.

Your task is: given the n and t print an integer strictly larger than zero consisting of n digits that is divisible by t. If such number doesn't exist, print  - 1.

Input

The single line contains two numbers, n and t (1 ≤ n ≤ 100, 2 ≤ t ≤ 10) — the length of the number and the number it should be divisible by.

Output

Print one such positive number without leading zeroes, — the answer to the problem, or  - 1, if such number doesn't exist. If there are multiple possible answers, you are allowed to print any of them.

Examples

input

3 2

output

712

Problem link : https://codeforces.com/problemset/problem/584/A

Solution :

• C++

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n,t,i;
    cin>>n>>t;
    if(t==10)
    {
        if(n==1)
        {
            cout<<-1<<endl;

        }
        else{

            for(i=0;i<n-1;i++)
            {
                cout<<1;
            }
            cout<<0<<endl;
        }
    }
    else{
        for(i=0;i<n;i++)
        {
            cout<<t;
        }
        cout<<endl;
    }
    return 0;
}